Ciprofloxacin-Resistant Kerstersia gyiorum Isolated From a Chronic Wound in Brazil: A Case Report

Chronic ulcers are often difficult to heal. Many factors can contribute to the occurrence and persistence of these wounds, including overall immunity, increasing age, male sex, perfusion, and, especially, the presence of microorganisms infecting the wound.¹ The most frequently isolated microorganisms from all types of chronic wounds are Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli, and Corynebacterium spp.^2,3

In the past decade, there have been reports in the literature of Kerstersia gyiorum causing otitis media, urinary tract infection, post-ulcer bacteremia, and sepsis as well as being present in bronchoalveolar lavage fluid and chronic wounds, causing colonization or infection.^4–9 This microorganism has been found in the United States, Turkey, Tanzania, Belgium, and Argentina.^{4–6,8,10,11}K gyiorum was shown to be a distinct species by examination of the isolates obtained from 9 clinical specimens, including leg ulcer swab, sputum, and feces, by cellular fatty acid analysis and 16S rRNA gene sequencing.^7–12 

The first study to classify K gyiorum was performed in chronic leg wound isolates.¹⁰Gyiorum (meaning “from the limbs”) was selected as the name of the species because the majority of strains were isolated from human leg wounds.^12,13 Case reports have highlighted the difficulty in establishing diseases caused by K gyiorum.⁸ Little is known about how the microorganism contributes to the chronicity of wounds, and its virulence factors have not yet been identified.⁶ In addition to increasing the understanding about its virulence and potential role in causing wound infections, more research is necessary to clarify 1) the relationship between K gyiorum and the sites where it has been found in humans and 2) the susceptibility profile in order to generate data for evidenced-based practice.

In the case study presented here, the objective was to evaluate the antimicrobial susceptibility profile of K gyiorum isolated from a chronic wound. 

Patients from a consecutive sample (N = 35) were evaluated for S aureus, P aeruginosa, and other microorganisms as a part of a study, the purpose of which was to evaluate the prevalence of microorganisms. Samples were collected via swabs, which were placed into Stuart transport medium followed by inoculation in tryptic soy broth and incubation at 35ºC (±2)/ON. An aliquot of the bacterial suspension was streaked onto tryptic soy agar. K gyiorum was identified by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) on Microflex LT software version 3.0 (Bruker Daltonics, Leipzig, Germany). Identification was confirmed by 16S rRNA partial sequence analysis.

Initially, antimicrobial susceptibility was determined by the disk diffusion test.¹⁴ However, K gyiorum is an uncommon bacterium, classified as non-Enterobacteriaceae, and the disk diffusion method has not been systematically studied and is not currently recommended.¹¹ Therefore, the antimicrobial susceptibility for this microorganism was then determined by minimum inhibitory concentration (MIC) using the MicroScan WalkAway System (Beckman Coulter, Brea, CA) and ETEST method (bioMérieux, Marcy-l’Étoile, France) for the following agents: piperacillin-tazobactam, cefepime, imipenem, meropenem, ciprofloxacin, and colistin. MIC to ciprofloxacin was also determined by the broth macrodilution method, which is considered the gold standard.⁸ MIC breakpoints were those established by the Clinical and Laboratory Standards Institute for other non-Enterobacteriaceae (susceptible, MIC < 1 µg/mL; intermediate resistance, MIC = 2 µg/mL; and resistant, MIC > 4 µg/mL). 

This study was approved by the Research Ethics Committee of Antonio Pedro Hospital University under number 815.553 (CAAE: 33740214.2.0000.5243). The study conformed to the ethical conditions of the Helsinki Declaration. Patient permission was obtained by signing an informed consent form. 

K gyiorum was isolated in 1 patient. The patient, an 85-year-old woman, had chronic venous insufficiency and presented to an intermediate care unit in Niteroi City, Rio de Janeiro, Brazil. She did not have a diagnosis of either hypertension or diabetes mellitus, and had a right instep chronic wound of 14 cm² with wound duration of 6 months. The chronic wound was treated with polyurethane foam containing ibuprofen.

The patient did not take antibiotics for 3 months before sample collection. Anamnesis, physical examination, and assessment of the chronic wound showed 50% granulation tissue, 50% devitalized tissue in the wound bed, and sparse serosanguinous exudate. There was no foul odor, and pain was the only clinical sign of infection reported by the patient. Samples were collected for culture and subsequent analysis of the susceptibility profile. Different colonies were obtained, and some were easily identified as S aureus. Other colonies that were flat, convex with smooth margins, whose colors ranged from white to beige, and were classified as gram-negative and catalase-positive coccobacilli were identified as K gyiorum by MALDI-TOF (score of 2.1) and confirmed by 16S rRNA partial sequence analysis.

The isolated K gyiorum was susceptible to most of the antibiotics tested by the 2 methods (MicroScan and ETEST) (Table 1). However, MIC values for ciprofloxacin demonstrated different results; in the ETEST method, the isolate was classified as resistant (MIC = 32 µg/mL) and in the MicroScan method as intermediately resistant (MIC = 2 µg/mL). To better understand these results, the authors decided to determine MIC by the broth macrodilution method; once more, it was classified as resistant to ciprofloxacin, with an MIC of 8 µg/mL (Table 1).

The collection of clinical specimens from wounds for culture and the subsequent microbiological study of these isolates is important to identify the type of microorganisms present, screen for new microorganisms, and ascertain their susceptibility to antimicrobial agents, which can lead to choosing the correct therapeutic protocol.^3,13 In the current study, the bacterium collected from the leg wound was not associated with infection. The only presenting clinical sign was pain. However, some authors have demonstrated K gyiorum infection from different clinical sites, such as in urinary, pulmonary, and integumentary systems.^4–6 Previous case reports of K gyiorum showed that associated infection usually developed with a long-standing inflammatory condition; however, that was not the case in the current patient.^4–6,14

Resistance to ciprofloxacin was first described for K gyiorum by Pence et al.¹² That case study reported 2 K gyiorum: 1 isolated from otitis media that was fully resistant to ciprofloxacin (MIC = 32 µg/mL) and the other from a chronic wound (MIC = 4 µg/mL).¹² However, in both cases reported by Pence et al,¹² patients had been treated previously with ciprofloxacin. In 2014 in the United States, a case report described K gyiorum obtained from bronchoalveolar lavage that had intermediate susceptibility to ciprofloxacin (MIC = 2 µg/mL).⁵ In all cases described, MIC was determined by ETEST. Despite K. gyiorum not being present in a wound in the US study, that report points to ciprofloxacin resistance similar to what was found in the current study.

Likewise, resistance to ciprofloxacin has been largely described in Enterobacteriaceae due to frequent use of this antibiotic.^15–17 The main mechanism in fluoroquinolone resistance is the accumulation of mutations in the target enzymes, namely DNA gyrase and DNA topoisomerase IV. However, the presence of genes encoding efflux pumps has provided low levels of resistance to this class of antibiotics in E coli isolates over the past decade.^18,19 Therefore, as low levels of resistance to ciprofloxacin were detected in the isolated K gyiorum, the authors believe that genes encoding efflux pumps could be the major mechanism of ciprofloxacin resistance in the current case. It is important to emphasize that S. aureus collected together with K gyiorum only presented resistance to penicillin; thus, K gyiorum can be a reservoir of ciprofloxacin resistance genes.

A study in the United States related the first case of bacteremia and sepsis due to K gyiorum in a patient with chronic lower-extremity ulcers, which draws more attention to these microorganisms.⁸ It is difficult to establish if K. gyiorum was acting as a pathogen or if it was simply present in the wound, but based on the presenting clinical signs of the wound in this case and in other reports,^8,14 the authors suggest that in this case, K gyiorum was just present in the wound, not causing an important inflammatory response or infectious process.

To the authors’ knowledge, there are few published scientific articles on K gyiorum, and the articles that were found are case studies. Hence, it is not possible to establish causal relationships among chronicity, infection, or inflammatory processes and K gyiorum. More research is needed to ascertain the clinical effects and potential treatment of wounds containing K gyiorum.

Cultures from a series of 35 patients with chronic lower leg wounds identified 1 patient with ciprofloxacin-resistant K gyiorum. The wound was not clinically infected. To the authors’ knowledge, this is the first study to describe ciprofloxacin-resistant K gyiorum in Brazil. Awareness about the emergence of K gyiorum is important, and more research is needed to ascertain the clinical effects and potential treatment of wounds containing K gyiorum.

The authors thank Isis Hazelman Vieira dos Anjos for help in the MALDI-TOF experiments.

Dr. Pires is a professor, Faculty of Nursing, State University of Rio de Janeiro, Brazil; Dr. B. Oliveira is a professor, School of Nursing Aurora of Afonso Costa, Fluminense Federal University, Niterói, Brazil; Dr. F. Oliveira is a nurse, São Lucas Hospital, Rio de Janeiro, Brazil; Ms. Silva is a doctoral student, Fluminense Federal University, Niterói, Brazil; Mr. Peloso is a biologist, Richet Laboratory, Rio de Janeiro, Brazil; Dr. Teixeira-Carvalho is a professor, Microbiology Laboratory Paulo de Góes, Federal University of Rio de Janeiro; Dr. Paula and Dr. Teixeira are professors, Faculty of Pharmacy, Fluminense Federal University, Niterói, Brazil. Address all correspondence to: Bruna Maiara Ferreira Barreto Pires, BSN, PhD, Departamento de Enfermagem Médico-Cirúrgica, Universidade do Estado do Rio de Janeiro, Boulevard 28 de setembro, 157, Vila Isabel, 20551-030 – Rio de Janeiro, RJ – Brasil; tel/fax: 55 (21) 2868-8236; email: bruna.barreto07@gmail.com.

This work was supported by the Conselho Nacional de Pesquisa e Desenvolvimento (CNPq) (grant number: 5526664/2011-1) and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) (grant number: E 26/010.002812/2004).